Quicktime

On my iMAC I use Photos for viewing my Dashboard Camera Videos. When I double click on one segment it is brought up using QuickTime which presents a larger video. On my MBP when I click on a segment it only runs from within Photos. If I move a segment onto the desktop I can right click and view using QuickTime.

Why does the iMAC automatically bring up QuickTime while the MBP does not? On the MBP it indicates that QuickTime Player 7 is the default.

All comments are welcome.